Application of Pneumatic Ball Valve in Vibration Equipment
At present, the application scope of pneumatic ball valve is more and more extensive, especially in some vibration equipment, pneumatic ball valve has become one of the indispensable equipment. Therefore, it is necessary to discuss the application of pneumatic ball valve in vibration equipment, which is necessary to improve the application effect.
2、 Structure and characteristics of pneumatic ball valve
Pneumatic ball valve is an elastic element that uses the reaction force of compressed air inside the pneumatic ball valve as the elastic restoring force. Pneumatic ball valve is widely used in power machinery, electronic equipment, instrumentation, chemical machinery and other equipment in the fields of automobile, railway vehicles, ships, aviation, industry, etc. due to its good vibration reduction and isolation performance.
1. Construction mode of pneumatic ball valve
Pneumatic ball valve is a non-metallic ball valve that is filled with air with certain pressure in a flexible bag and uses the compressibility of air to complete the elastic function. Pneumatic ball valves are mainly divided into two categories: bag type pneumatic ball valves and membrane type pneumatic ball valves.
In today's mechanical design process, pneumatic ball valves, like gears, can be regarded as specifications. Corresponding pneumatic ball valves can be selected according to the weight of the load and the size of the geometric device.
2. Characteristics of pneumatic ball valve
(1) The elastic coefficient of pneumatic ball valve is variable. With the increase of the load, the elastic coefficient also increases. The pneumatic ball valve can design various characteristic curves to meet various performance requirements, because the pneumatic ball valve has nonlinear characteristics.
(2) The body of the pneumatic ball valve is relatively light, and the air quality is also very small. Most of the weight of the pneumatic ball valve comes from the upper cover and the lower cover. Unlike the steel ball valve, the metal weight is relatively heavy.
(3) The bearing capacity of the pneumatic ball valve can be adjusted according to the inflation pressure in the pneumatic ball valve. For the same pneumatic ball valve, the inflation pressure can be adjusted to meet different bearing capacity requirements.
(4) Since the pneumatic ball valve uses air as the elastic medium, when it is compressed, the internal friction is small, so the vibration isolation characteristics are comparable. In addition, the pneumatic ball valve has a good ability to eliminate noise, because the ability to transmit air and sound is relatively weak.
(5) The anti fatigue ability of pneumatic ball valves is relatively strong. Experiments show that the acceptable stress cycles of ordinary steel plate ball valves are 500000 to 600000 times, while that of ordinary pneumatic ball valves can reach about 3 million times, and that of high-performance pneumatic ball valves can reach more than 5 million times. Therefore, pneumatic ball valve plays a prominent role in resisting strain.
(6) However, the manufacturing process of pneumatic ball valve is demanding and complex, so the cost is high.
3、 Control system of pneumatic ball valve
The control system of pneumatic ball valve has undergone two innovations with the progress of other related technologies, and experienced three development stages: mechanical control, electronic control and intelligent control. However, no matter what kind of control system, it generally includes three sub modules: air supply system (air source), control components (including software), and safe installation (to ensure the normal operation of pneumatic ball valve). The air source and safe installation of the three control systems will be different with different control components, but their most basic difference is the control components. As for the mechanical control system, its control components are mainly height control valves, which can automatically stop the inflation and exhaust of the pneumatic ball valve to complete the height control of the pneumatic ball valve; The electronic control system has taken a big step forward compared with the mechanical control system, which is a qualitative leap. It uses the electronic controller (ECU) to collect signals from various sensors, stop analyzing the signals, and send the control signals to the actuator (mainly various solenoid valves) to complete the control of the pneumatic ball valve; The intelligent control system is developed on the basis of the electronic control system with the help of today's automatic control theory. It mainly improves the software of the ECU. It can not only control the height and rigidity of the pneumatic ball valve, but also control the nonlinear characteristics of the pneumatic ball valve by applying control technologies such as fuzzy neural network.
4、 Analysis of several influencing factors
The proportion of the volume of the air chamber and the additional air chamber, the shape, data and size of the pneumatic ball valve, and the size of the orifice between the air chamber and the additional air chamber have a certain impact on the system stiffness and natural frequency.
1. The influence of the stiffness of the spring capsule data on the first order resonant frequency of the system. The experiment shows that the stiffness of the pneumatic ball valve data has a great influence on the stiffness of the pneumatic ball valve, which is the reason why the theoretical value of the stiffness of the pneumatic ball valve differs greatly from the experimental value. The greater the stiffness of the pneumatic ball valve data, the greater the stiffness of the pneumatic ball valve, and the higher the first-order resonance frequency, which results in the improvement of the minimum operating frequency of the system. Therefore, the pneumatic ball valve isolation system should reduce the data stiffness and natural vibration frequency, so that the minimum operating frequency of the system is as low as possible under the condition that the bearing capacity of the flawless ball valve isolator can leave enough margin.
2. When the vibration table vibrates laterally, the stiffness of the spring capsule data is much greater. The main body of the pneumatic ball valve is soft, so it has a comprehensive vibration isolation effect in axial, transverse and rotary directions. When the mechanical vibration table vibrates laterally, the spring capsule data stiffness is much larger.
3. An orifice is set between the pneumatic ball valve and the additional air chamber. When air flows through the orifice, it will absorb a local vibration energy due to resistance, thus playing the role of vibration damping. In addition to affecting the stiffness and natural frequency of the system, the size of the orifice mainly affects the damping of the system.
The system stiffness decreases with the increase of the orifice opening, and the damping first increases and then decreases with the increase of the orifice. The increase of the volume of the additional air chamber can reduce the system stiffness and increase the damping ratio. The increase of the incentive frequency will increase the system stiffness and reduce the system damping ratio. The change of static load has little effect on the system vibration characteristics.